Composite cement and preparation method thereof

Abstract

The invention relates to a type of cement and a preparation method thereof, and particularly relates to a composite cement and a preparation method thereof, belonging to the technical field of building materials. The composite cement obtained by grinding 46-70 parts of portland cement clinker, 4-8 parts of gypsum, 10-15 parts of activated sludge, 10-30 parts of fly ash, and 2-5 parts of limestone until the specific surface area is greater than 300 m<2> / Kg is high in early strength, thus solving the key technical problems that the early strength of the composite cement is increased and water for treating sludge is effectively utilized. The compressive strengths of the composite cement achieve 17-25 MPa and 45-60 MPa, and the flexural strengths of the composite cement achieve 3.5-5 MPa and 6-8 MPa in 3 days and 28 days respectively; and the composite cement is provided with a micro-expansion characteristic, is capable of giving compensating shrinkage performance to mortar and concrete, and improving the anti-crack capacity of mortar and concrete, and is suitable for production for mortar, concrete and products.

Description

technical field [0001] The invention relates to a cement and a preparation method thereof, in particular to a composite cement and a preparation method thereof, and belongs to the technical field of building materials. Background technique [0002] Composite Portland cement is a hydraulic cementitious material made of Portland cement clinker, two or more specified mixed materials and an appropriate amount of gypsum. It is called composite Portland cement, or composite cement for short. Composite cement contains 20%-50% mixed materials, which promotes the recycling of industrial waste residues and reduces carbon dioxide emissions and production energy consumption during the production of cement clinker. However, due to the pozzolanic reaction between calcium hydroxide produced by cement hydration and the mixed materials usually occurs in the middle and late stages of cement hydration, the early strength of composite cement is low. The adverse effect of a large amount of mixe...

AI Technical Summary

Problems solved by technology

However, due to the pozzolanic reaction between the calcium hydroxide produced by cement hydration and the mixed materials usually occurs in the middle and late stages of cement hydration, the early strength of composite cement is low

The adverse effect of a large amount of mixed industrial waste is also manifested in the lower flexural strength of cement, which increases the risk of shrinkage and early cracking of mortar and concrete

After searching, the applicant found that an article titled "Production of Ecological Cement from Residual Activated Sludge in Urban Sewage Plants (Journal of Chemical Industry, Vol. 62, No. 4)" disclosed the technology of using domestic sewage treatment plant sludge to burn cement. Adding less than 10% of activated sludge into the feed can increase the burnability of the raw meal and reduce the liquid phase formation temperature. Although the formation of f-CaO is significantly reduced, the content of C2S is increased and the content of C3S is reduced. The cementitious mineral components in cement change, and the incorporation of sludge affects the lattice structure of cement clinker, prolonging the setting time of cement

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